Gas-phase polymerization of C2-C8-alk-1-enes

Abstract

In a process for the polymerization of C 2 -C 8 -alk-1-enes by means of a Ziegler-Natta catalyst system, in which polymerization is carried out from the gas phase in at least one reaction zone at from 40 to 120° C. and pressures of from 1 to 100 bar, the pressure and temperature in the reaction zone are set so that an operating point formed by these parameters in a pressure-temperature diagram is located at from 0.2 to 5.0 bar below the dew line of the respective reaction mixture above which condensation of the C 2 -C 8 -alk-1-enes occurs.

We claim:  
     
       1. A process for the polymerization of C 2 -C 8 -alk-1-enes by means of a Ziegler-Natta catalyst system, in which polymerization is carried out from the gas phase in at least one reaction zone at from 40 to 120° C and pressures of from 1 to 100 bar, wherein the pressure and temperature in the reaction zone are set so that an operating point formed by these parameters in a pressure-temperature diagram is located at from 0.2 to 5.0 bar below the dew line of the respective reaction mixture above which condensation of the C 2 -C 8 -alk-1-enes occurs, wherein the reaction zone is a stirred powder-bed reactor, and RCE-BIDELL et al., Ser. No. 09/525,063 wherein the Ziegler-Natta catalyst system comprises a titanium-containing solid component a) and also cocatalysts in the form of organic aluminum compounds b) and electron donor compounds c). 
     
     
       2. A process as claimed in  claim 1 , wherein the operating point is formed by pressure and temperature in the pressure-temperature diagram is located from 0.5 to 2.5 bar below the dew line of the respective reaction mixture. 
     
     
       3. A process as claimed in  claim 1  used for preparing homopolymers of propylene. 
     
     
       4. A process as claimed in  claim 1  used for preparing copolymers of propylene with subordinate amounts of other C 2 -C 8 -alk-1-enes. 
     
     
       5. A process as claimed in  claim 1 , wherein the polymerization is carried out at from 40 to 100° C. 
     
     
       6. A process as claimed in  claim 1 , wherein the polymerization is carried out at pressures of from 10 to 50 bar. 
     
     
       7. A process as claimed in  claim 1 , wherein the molar mass of the C 2 -C 8 -alk-1-ene polymers formed is set by means of hydrogen as regulator. 
     
     
       8. A process as claimed in  claim 1 , wherein the polymerization of the C 2 -C 8 -alk-1-enes is carried out in two reactors connected in series.